An important theme of conventional methods for manufacturing a silicon-crystal solar battery is to reduce the manufacturing cost, and as one of these methods, there has been known a method for forming an electrode by coating a metal paste by a screen printing method and thereafter sintering the metal paste (see, for example, Patent Literature 1). In Patent Literature 1, a paste containing silver as a main component is printed in a comb shape onto a reflection prevention film formed on a light receiving surface of a silicon substrate on which a pn-junction is formed, and the paste is dried. Further, a paste containing aluminum is printed onto an area of a major portion of a back surface of the silicon substrate, and the paste is dried. Thereafter, a paste containing silver is printed at positions where the paste containing aluminum is not printed, and the paste is dried. Thereafter, by sintering, on a front surface of the silicon substrate, front surface electrodes are formed by a fire-through method for conducting printed silver to silicon at a base by penetrating through a reflection prevention film which is insulated. On the back surface of the silicon substrate, as a back surface electrode, back-surface current-collection electrodes are formed at positions where the paste containing aluminum is formed; and back-surface extraction electrodes are formed at the positions where the paste containing silver is formed. At the same time, in a region where the paste containing aluminum is formed, a BSF (Back Surface Field) layer that can prevent recoupling of minority carriers that are generated by light irradiation in the silicon substrate, is formed.
Furthermore, in recent years, a technique for forming a back surface electrode of a solar battery by a method referred to as an LFC (Laser Fired Contact) method has been known (see, for example, Non Patent Literature 1). In this method, an insulation film is formed on the entire back surface of a silicon substrate by a CVD (Chemical Vapor Deposition) method. Further, an aluminum film is deposited on the entire surface of the insulation film, and only a necessary portion is melt by irradiating laser light, thereby forming a back surface electrode; such that aluminum electrodes formed on the entire back surface, are conducted to the silicon substrate at many points; or such that aluminum electrodes formed in a comb shape on the back surface, are conducted to the silicon substrate.